Trialkylsilyloxy-1,1-diphenyl ethylenes and polymers produced therewith

ABSTRACT

Trialkylsilyloxy-1,1-diphenyl ethylenes corresponding to general formula I, new polymers produced therewith terminated by aryl trialkylsilyl ether groups or by phenolic hydroxyl groups and a process for the production of these polymers by anionic polymerization ##STR1## in which R 1 , R 2  =H, C 1  -C 4  alkyl, OCH 3 , 
     R 3  =H, C 1  -C 4  alkyl, O--C 1  -C 4  alkyl, 
     R 4  =H, C 1  -C 4  alkyl, 
     R 5  =C 1  -C 4  alkyl, 
     R 6  =H, C 1  -C 4  alkyl.

This invention relates to trialkylsilyloxy1,1-diphenyl ethylenescorresponding to general formula I and to new polymers producedtherewith terminated by aryl trialkylsilyl ether groups or by phenolichydroxyl groups and to a process for the production of these polymers byanionic polymerization. ##STR2## in which R¹, R² =H, C₁ -C₄ alkyl, OCH₃,

R³ =H, C₁ -C₄ alkyl, O--C₁ -C₄ alkyl,

R⁴ =H, C₁ -C₄ alkyl,

R⁵ =C₁ -C₄ alkyl,

R⁶ =C₁ -C₄ alkyl.

German Offenlegungsschrift 37 25 848 describes the production ofpolymeric dihydroxy compounds by anionic polymerization of suitablecompounds, reduction of the reactivity of the polyanion by 1,1-diphenylethylene in an optional step, reaction with 2,5-dimethoxy benzyl bromideand removal of the protective group by subsequent ether cleavage withtrimethyl iodosilane, trimethyl chlorosilane or sodium iodide or acids.

The compounds are suitable as stabilizers for polymers, particularlythose containing unsaturated bonds in the polymer chain, againstthermal, radiation-induced and oxidative degradation.

The reaction of so-called "living" polymers (such as polystyryl lithium)with halogen compounds containing other functional groups givesfunctional polymers, but is accompanied by a number of secondaryreactions (cf. J. Polym. Sci. A 3, 4131 (1965); Polymer 17, 1020 (1976);J. Polym. Sci. B 14, 471 (1976; Adv. Polym. Sci. 56, 72 (1984)). Theyield of functional polymer is often not satisfactory. Accordingly, thisreaction is not suitable for large scale manufacture.

The present invention relates to trialkylsilyloxy-1,1-diphenyl ethylenescorresponding to formula (I), to polymers produced therefrom terminatedby aryl trialkylsilyl ether groups or by phenolic hydroxyl groupscorresponding to formulae (II) and (III) and to corresponding productionprocesses. ##STR3## in which

A=a polymer of anionically polymerizable vinyl compounds,

R¹, R² =H, C₁ -C₄ alkyl, OCH₃,

R³ =H, C₁ -C₄ alkyl, O--C₁ -C₄ alkyl,

R⁴ =H, C₁ -C₄ alkyl,

R⁵ =C₁ -C₄ alkyl,

R⁶ =H, C₁ -C₄ alkyl

R⁷ =H, Si(R⁵)₃.

The trialkylsilyloxy diphenyl ethylenes of formula (I) according to theinvention may be obtained by methods known per se. Hydroxy diphenylethylenes corresponding to formula (V) may be obtained by thealkali-catalyzed thermal cleavage of1-alkyl-1-phenyl-bis-(hydroxyphenyl)-methane corresponding to formula(IV) (DE-AS 1 235 894): ##STR4## In formulae IV and V, R¹, R², R³, R⁴and R⁶ are as defined above.

The trialkylsilyloxy-1,1-diphenyl ethylenes (I) are formed by reactionof the hydroxy diphenyl ethylenes corresponding to formula (V) withhalosilanes corresponding to formula (VI) in the presence of acidacceptors (I). ##STR5## Hal=Cl, Br.

Accordingly, the starting products for the production of the compoundsof formula (I) according to the invention are1-alkyl-1-phenyl-bis-(hydroxyphenyl)-methanes corresponding to formula(IV), in which the substituents R¹ to R⁶ are as defined above.

The following are examples of compounds corresponding to formula (IV):

1-methyl-1-phenyl-bis-(4-hydroxyphenyl)-methane,

1-ethyl-1-phenyl-bis-(4-hydroxyphenyl)-methane,

1-propyl-1-phenyl-bis-(4-hydroxyphenyl)-methane,

1-pentyl-1-phenyl-bis-(4-hydroxyphenyl)-methane,

1-methyl-1-(4-methylphenyl)-bis-(4-hydroxyphenyl)-methane,

1-methyl-1-(4-methoxyphenyl)-bis-(4-hydroxyphenyl)-methane,

1-methyl-1-(3,5-dimethylphenyl)-bis-(4-hydroxyphenyl)methane,

1-methyl-1-phenyl-bis-(2-hydroxyphenyl)-methane,

1-methyl-1-phenyl-[(4-hydroxyphenyl)-(2'-hydroxyphenyl)]methane,

1-methyl-1-phenyl-bis-(3-methyl-4-hydroxyphenyl)-methane,

1-methyl-1-phenyl-bis-(3-methoxy-4-hydroxyphenyl)-methane,

1-methyl-1-phenyl-bis-(3,5-dimethyl-4-hydroxyphenyl)methane,

1-methyl-1-phenyl-bis-(3,5-dimethyl-2-hydroxyphenyl)methane.

Preferred compounds corresponding to formula (IV) are those containingthe following substituents:

R¹ =H,

R² =H, CH₃, OCH₃,

R³ =H, CH₃, OCH₃,

R⁴ =H, CH₃,

R⁶ =H, CH₃.

More preferably, R¹, R², R³, R⁴ and R⁶ are hydrogen.

The compounds corresponding to formula (IV) may be cleaved under theconditions described in DE-AS No. 1 235 894. Suitable halosilanes forthe reaction of the compounds corresponding to formula (V) to thetrialkylsilyloxy diphenyl ethylenes of formula (I) according to theinvention correspond to formula (VI).

Examples of halosilanes corresponding to formula (VI) are trimethylchlorosilane, triethyl bromosilane, tripropyl chlorosilane, diethylmethyl chlorosilane. Trimethyl chlorosilane and triethyl chlorosilaneare preferred, trimethyl chlorosilane being particularly preferred.

Compounds corresponding to formula (V) may generally be reacted withthose of formula (VI) in a molar ratio of 1:1 (or with a slight excessof (VI)) in inert solvents, such as hydrocarbons (gasoline, ligroin,heptane, pentane, cyclohexane, benzene, toluene, xylene), halogenatedhydrocarbons (chloroform, methylene chloride, dichloroethane,chlorobenzene) or ethers (diethyl ether, diisopropyl ether, dibutylether); the reaction is preferably carried out in hydrocarbons in thepresence of a base, such as ammonia, triethyl amine, tributyl amine,pyridine, N-methyl imidazole, quinoline. However, the compound offormula (V) may also be converted into a salt and the salt reacted indry form with the halosilane. Apart from the amine salts mentionedabove, suitable salts are also salts of lithium, sodium and potassium.

The reaction temperature is in the range from 0° to 120° C. andpreferably in the range from 10° to 100° C.

The base must be used in an at least stoichiometric quantity based on(V), best in a slight excess.

After separation of the salts formed during the reaction, for example byfiltration, the compounds corresponding to formula (I) may be directlyused as such, although additional purification by distillation ispossible.

The following are examples of suitable compounds of formula (I) for theproduction of the new polymers:

4-methyl-4'-trimethylsilyloxy-1,1-diphenyl ethylene,

4-ethyl-4'-triethylsilyloxy 1,1-diphenyl ethylene,

3-methoxy-4'-trimethylsilyloxy-1,1-diphenyl ethylene,

4-isopropyl-4'-triethylsilyloxy 1,1-diphenyl ethylene,

4-methyl-2'-trimethylsilyloxy-5'-methyl 1,1-diphenyl ethylene,

3-methyl-4-trimethylsilyloxy-1,1-diphenyl ethylene,

4-methoxy-2'-trimethylsilyloxy-3',5'-dimethyl 1,1-diphenyl ethylene,

3-methoxy-4-trimethylsilyloxy 1,1-diphenyl ethylene,

4-trimethylsilyloxy-β-methyl 1,1-diphenyl ethylene,

4-trimethylsilyloxy-β-propyl 1,1-diphenyl ethylene,

4-Trimethylsilyloxy-1,1-diphenyl ethylene is particularly preferred.

The process according to the invention for the production of thepolymeric compounds terminated by aryl trimethylsilyl ether groups or ofthe polymeric compounds terminated by phenolic hydroxyl groupscorresponding to formulae (II) and (III) involves the following steps:

1. Preparation of a polyanion by anionic polymerization of a suitablevinyl compound.

2. Reaction of the polyanion with a compound corresponding to formula(I) ##STR6## in which R¹ to R⁶ are as defined above.

3. Neutralization of the reaction products (which are themselvespolyanions) with protic compounds to form the polymeric compoundsterminated by aryl trisilyloxy ether groups corresponding to formulae(II) and (III) in which R⁷ =Si(R⁵)₃.

4. Optionally, silyl ether cleavage for the production of the polymericcompounds terminated by phenolic hydroxyl groups corresponding toformulae (II) and (III) in which R⁷ =H.

In step 1, anionically polymerizable vinyl compounds are polymerized inaromatic or aliphatic hydrocarbons or an ether with an alkyl alkalimetal compound, aryl alkali metal compound or an oligomeric o-methylstyrene/alkali metal compound with formation of a "living" polyanion orpolydianion, the reaction being continued to complete conversion of themonomer. In step 2, the polyanion or polydianion is reacted withcompounds corresponding to formula (I), resulting in the formation of anew polyanion or polydianion. In step 3, the polyanion or polydianion isneutralized with protic compounds and the polymer (II) or (III)terminated by aryl trisilyloxy ether groups (R⁷ =Si(R⁵)₃) is isolated.

To produce the polymers (II) or (III) terminated by phenolic hydroxylgroups (R⁷ =H), the polyanion or dianion is neutralized after steps 1and 2 in step 3, the product is optionally isolated and the silyl etheris cleaved.

Suitable anionically polymerizable compounds in the context of theinvention are e.g. styrene, p-methyl styrene, vinyl pyridine, vinylnaphthalene, isopropenyl naphthalene, 1,3-butadiene, isoprene ormixtures thereof. Preferred are styrene, 1,3-butadiene, isoprene ormixtures of styrene/1,3-butadiene and styrene/isoprene. andstyrene/isoprene.

Suitable aromatic and aliphatic hydrocarbons in the context of theinvention are e.g. toluene, benzene, xylene, pentane, hexane,cyclohexane Ethers in the context of the invention are e.g.tetrahydrofuran and dioxane. A mixture of aromatic or aliphatichydrocarbons and ethers may also be used to adjust certain reactionvelocities.

To prepare the polymers corresponding to formula (II), alkyl alkalimetal compounds, particularly n-butyl lithium or sec.-butyl lithium, arepreferably used as initiators.

To prepare the polymer corresponding to formula (III), aryl alkali metalcompounds, particularly naphthalene sodium, naphthalene potassium,oligo-α-methyl styryl sodium, oligo-α-methyl styryl Potassium or1,3-Phenylen-bis(3-methyl-1-phenyl-pentyliden)bis(lithium), arepreferably used as initiators.

The anionically polymerizable compounds may be polymerized at -100° C.to +80° C. and preferably at -78° C. to 50° C.

The "living" polymer anions may be reacted with the compound (I) at -78°C. to +100° C. and preferably at 0° C. to 50° C. Compound (I) ispreferably used in excess, based on initiator.

Suitable neutralizing agents for the "living" polymer anions are, forexample, weak inorganic or organic acids, particularly methanol oracetic acid.

Since the process according to the invention uses "living" carbanions,it is of course necessary to maintain conditions under which "living"carbanions are stable, for example an inert atmosphere, absence ofatmospheric oxygen and moisture.

The, silyl ethers corresponding to formulae (II) and (III) (R⁷ =Si(R⁵)₃)may advantageously be cleaved by acidification of their solutions withinorganic acids (for example hydrochloric acid) or organic acids (forexample p-toluene sulfonic acid). The cleavage is carried out attemperatures in the range from room temperature to the boilingtemperature of the solvent.

The polymers of formulae (II) and (III) (R⁷ =H) according to theinvention may be isolated by precipitation of the polymer from thesolution, preferably using methanol, or by evaporation of the polymersolution in known evaporation units.

The polymers of formulae (II) and (III) according to the invention havemolecular weights (controllable through the ratio of monomerconcentration to initiator concentration) of from 500 g/mol to 500,000g/mol, preferably from 1000 g/mol to 250,000 g/mol and more preferablyfrom 1000 g/mol to 100,000 g/mol.

The polymers of formulae (II) and (III) according to the invention aresuitable as stabilizers and/or lubricants for synthetic polymers and (R⁷=H) for the build-up of polycondensates.

EXAMPLES 1.1 Preparation of1-methyl-1-phenyl-bis-(4-hydroxyphenyl)-methane

A mixture of 240 g (2 mol) acetophenone, 940 g (10 mol) phenol and 30 gmercapto propionic acid is saturated with HCl gas and, at the same time,is slowly heated to 50° C. The mixture is then kept under theseconditions for 5 hours and left standing overnight, after which firstHCl and water are distilled off in a water jet vacuum, followed by theexcess phenol up to a sump temperature of 120° C. The residue of 510 gis dissolved in and reprecipitated under reflux from 1250 ml toluene,filtered under suction after cooling and dried: 412 g, Mp. 185°-7° C.,i.e. 72% of the theoretical (MW 580).

1.2 Preparation of 4-hydroxy-1,1-diphenyl ethylene:

400 g of the triphenyl methane derivative obtained as described aboveare heated with 4 g NaOH to 180°-220° C. The cleavage products distillover at 130°-160° C. and approx. 15 mbar. A total of 340 g distillateand approx. 56 g of a brown resin-like residue are obtained.

A fraction of 120 g corresponding to the title compound compound isisolated from this distillate by redistillation (45% of the theoretical;MW 196).

1.3 Preparation of 4-trimethylsilyloxy-1,1-diphenyl ethylene

100 g (0.51 mol) of the 4-hydroxy-1,1-diphenyl ethylene, obtained bycleavage are dissolved in 200 ml cyclohexane, 56 g (0.56 mol) triethylamine are added to the resulting solution and 56 g (0.56 mol) trimethylchlorosilane are added dropwise thereto over a period of about 1 h atroom temperature to 50° C. After another 2 h at 50° C., the saltprecipitated is filtered off under pressure, the filter cake isthoroughly washed with cyclohexane and the entire filtrate is distilled.Redistillation of the main fraction, Bp₁.5 143°-8° C., gives 110 g of acolorless liquid (n_(D) ²⁰ =1.5558) which, according to NMR, correspondsto the title compound and is at least 95% pure (67% of the theoretical).

1.4 Reaction of a "living" polystyrene anion with 4-trimethylsilyloxydiphenyl ethylene (preparation of the polymer of formula (II) with R⁷=Si(R⁵))

6.5 ml of a 2.5 molar n-butyl lithium solution (in hexane) wereintroduced by syringe with rapid stirring at room temperature in anitrogen atmosphere into a mixture of 800 ml toluene and 100.2 gstyrene, the solution turning orange-red in color. The temperature wasthen increased to 40° C. After a polymerization time of 3 h, thesolution was brought to room temperature and 45 ml of a solution of 10 g4-trimethylsilyloxy-1,1-diphenyl ethylene and 69 g toluene were added bymeans of a syringe, the solution turning dark red in color. The reactiontime was 1 h at room temperature. The polymer was then neutralized with2 ml methanol (nitrogen-saturated) and isolated by pecipitation inmethanol.

1.5 Cleavage of the silyl ether (preparation of a polymer of formula(II) (R⁷ =H)

20 ml of a 10% aqueous hydrochloric acid were added at 40° C. to asolution of 100 g of the polymer described in the above Example in 800ml tetrahydrofuran. The reaction time was 1 h. The polymer was thenprecipitated in methanol, washed until neutral and dried.

GPC analysis (calibration: polystyrene)

M_(n) =6 500 g/mol, `M_(w) =7 900 g/mol.

2.1 Reaction of a "living" polystyrene dianion with4-trimethylsilyloxy-1,1-diphenyl ethylene (preparation of the polymer offormula (III) with R⁷ =Si(R⁵)₃)

4 g (0.031 mol) naphthalene are added under nitrogen to 0.55 g (0.024mol) sodium in 250 ml tetrahydrofuran, the solution turning bright greenin color. After about 2 h at room temperature, the sodium had completelyreacted to naphthalene sodium. 50 g styrene were then added dropwise bysyringe over a period of 2 h, the color turning to red. After another 30minutes, a solution of 8 g (0.03 mol) 4-trimethyl silyloxy-1,1-diphenylethylene and 15 ml toluene was added by syringe. After a reaction timeof 2 h at room temperature, the polymer was neutralized with methanol(nitrogen-saturated) and isolated by precipitation in methanol.

2.2 Cleavage of the silyl ether (preparation of the polymer of formula(III) with R⁷ =H))

35 ml of 10% aqueous hydrochloric acid were added at 40° C. to asolution of 45 g of the polymer described in the above Example in 350 mltetrahydrofuran. After a reaction time of 1 hour, the polymer wasprecipitated in methanol, isolated, washed until neutral and dried.

We claim:
 1. Trialkylsilyloxy-1,1-diphenyl ethylenes correspondingformula (I) ##STR7## in which R¹, R² =H, C₁ -C₄ alkyl, OCH₃,R³ =H, C₁-C₄ alkyl, O-C₁ -C₄ alkyl, R⁴ =H, C₁ -C₄ alkyl, R⁵ =C₁ -C₄ alkyl, R⁶ =H,C₁ -C₄ alkyl.
 2. Trialkylsilyloxy-1,1-diphenyl ethylenes as claimed inclaim 1, in which R¹ =H; R² =H, CH₃, OCH₃ ; R⁴ =H, CH₃ ; R⁵ =C₁ -C₄alkyl and R⁶ =H, CH₃.
 3. Trialkylsilyloxy-1,1-diphenyl ethylenes asclaimed in claim 1, in which R¹, R², R³, R⁴ and R⁶ are hydrogen and R⁵is CH₃.